<%@page import="java.io.OutputStream"%>
<%@ page contentType="image/jpeg" import="java.awt.*, java.awt.image.*,java.util.*,javax.imageio.*"  pageEncoding="UTF-8"%>
<%!
    Color getRandColor(int fc,int bc)
    {
        Random random = new Random();
        if(fc>255) fc=255;
        if(bc>255) bc=255;
        int r=fc+random.nextInt(bc-fc);
        int g=fc+random.nextInt(bc-fc);
        int b=fc+random.nextInt(bc-fc);
        return new Color(r,g,b);
    }
%>
<%
    response.setHeader("Pragma","No-cache");
    response.setHeader("Cache-Control","no-cache");
    response.setDateHeader("Expires", 0);
    int width=60, height=20;
    BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
    Graphics g = image.getGraphics();
    Random random = new Random();
    g.setColor(getRandColor(200,250));
    g.fillRect(0, 0, width, height);
    g.setFont(new Font("Times New Roman",Font.PLAIN,18));
    g.setColor(getRandColor(160,200));

    for (int i=0;i<155;i++) {
        int x = random.nextInt(width);
        int y = random.nextInt(height);
        int xl = random.nextInt(12);
        int yl = random.nextInt(12);
        g.drawLine(x,y,x+xl,y+yl);
    }

    String sRand="";
    for (int i=0;i<4;i++){
        String rand=String.valueOf(random.nextInt(10));
        sRand+=rand;
        g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
        g.drawString(rand,13*i+6,16);
    }
    //设置进入session属性
    //注意名称
    session.setAttribute("rand",sRand);
    g.dispose();
    OutputStream os = response.getOutputStream();
    ImageIO.write(image, "JPEG", os);

    //解决非法状态exception
    os.flush();
    os.close();
    os=null;
    response.flushBuffer();
    out.clear();
    out = pageContext.pushBody();
    }
    catch(IllegalStateException e)
    {
    System.out.println(e.getMessage());
    e.printStackTrace();
%>